As a former owner of a 1970 440 Charger, I can maybe ease you'r dillema. The stock 440 Magnum was underated at 375 HP. But B-Bodies are very heavy (empty weight on my title said 3750). Unless other gear ratios are or were ordered they usually came with 323's.
Most came in automatic (727 Tourquflight) transmissions. Mine was basically bone stock and like every other big Mopar it was hella fast when rolling but did not seem like a worldbeater off of the line. I never took mine to the track and have nothing to go on but others I raced and seat of the pants but it seeemed like a low 14 second car possibly high 13's. Had a budy with a 71 Roadrunner and he ran high 13's and low 14's with a ton of wheelspin on radials. That seemed the norm for most big B-Bodies that were close to stock.
So if you take him out of the hole you should kill him with the times you'r car is putting down. The best part is win or loose it will be one helluva fun time
1994 Cobra